Device and Method for the Quantity-Controlled Filling of Containers with Powdered Substances

ABSTRACT

A device for the controlled filling of containers with powdered substance includes a supply vessel with a narrow exit opening for temporarily holding the powdered substance and for discharging a predetermined quantity of the powdered substance into a container located underneath the supply vessel, a vibrator means is connected to the supply vessel for effecting the discharge of the powdered substance. A sensor for determining the quantity of powdered substance discharged from the supply vessel into the container, and a control unit, which converts the data acquired by the sensor into control commands for the vibrator means is included. The sensor includes a capacitive sensor for the quantitative determination of the quantity of powdered substance falling there through during the filling process and is located between the supply vessel and the container.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority based on European patent applications EP 07 017 104.6, filed Aug. 31, 2007, and EP 08 014 296.1, filed oil Aug. 11, 2008.

FIELD OF THE INVENTION

The invention pertains to a device and to a method for the controlled filling of containers with powdered substances.

Strict quality criteria must be met in the production of powdered pharmaceutical products. Various inspection methods test the powdered substances to determine, for example, their active ingredient or other content before they are packaged in their final containers. Blister packs are used for this purpose among other types of packaging methods.

To exclude errors during the final step of filling the containers, a sensor is used to verify the quantity of material in the pockets of a blister pack. This sensor is described in EP 1 193 77 A1. After the sensor has checked the quantity of material in the pockets of the blister pack, the pockets are sealed. An example of a sensor of this type is a capacitive measuring sensor.

U.S. Pat. No. 4,461,363 describes a filling device, in which the powder is first metered into recesses in a rotatable filling unit, as can be seen in FIG. 6. The filling unit is rotated, and the powder is discharged pneumatically downward into a container. As it is falling, the powder is inspected by a capacitive measuring sensor to ensure that the quantity is correct.

The article “On the rate of descent of powder in a vibrating tube” by S. Yang and J. R. G. Evans, Philosophical Magazine, Vol. 85, No. 10, Apr. 1, 2005, pp. 1089-1109, describes a device for filling containers with powder in which the powder is held temporarily in a glass vessel with a narrow tip and then transferred downward into the container through an exit opening. The exit opening is narrow such that the cohesiveness of the powder prevents it from flowing under the effect of gravity. A vibration device connected to the glass vessel is included to turn the powder stream on and off. The container is positioned on a weighing device, which determines the total weight of the container and from that value derives the quantity of powder which has been transferred thereto. The vibration device is controlled on the basis of this calculation. The system suffers from the problem of a long weighing time for small quantities of powder. Furthermore, the system can not be used in the area of antiseptic or sterile production, as the weighing cells cannot be sterilized in-line. Another short coming is that certain types of containers cannot stand free of attachment or support on a weighing cell.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a device for the controlled filling of containers with powdered substances such that the powdered substances are subjected to rapid quantitative inspection during the filling process. In addition, it is an object of the present invention to provide a device for controlled filling of containers which allows the amount of powder transferred to the containers to be controlled accurately and reliably. It is a further object of the invention to provide a corresponding method for the controlled filling of containers with powdered substances.

According to an aspect of the invention, the device for the controlled filling of containers with powdered substance includes a supply vessel with a narrow exit opening for holding the powdered substance and for discharging a predetermined quantity of the powdered substance into at least one container located below the supply vessel. The device also includes vibrator means, connected to the supply vessel, for effectuating the discharge of the powdered substance. A sensor for determining the quantity of powdered substance discharged from the supply vessel into the container and a control unit, which is adapted to convert the data acquired by the sensor into control commands for the vibrator means are also included. The sensor is a capacitive sensor for the quantitative determination of the amount or quantity of powdered substance falling through it during the filling process and is located between the supply vessel and the container. The device of the present invention provides an accurate determination of the quantity of the powdered substance as it is falling into the container despite any irregular distribution, local splitting or expansion of the cluster of the powdered substance. Accordingly, the method of the present invention is highly reliable and accurate. In addition, the device of the present invention provides for the precise, accurate and quick control of the filling process including discharge of the powdered substance. The device of the present invention can be used for a very wide variety of applications including but not limited to the filling of blister pockets, the filling of ring-shaped cassettes with several pockets for individual doses, and the filling of other types of multi-unit containers. The device of the present invention may also be used to fill any container with a narrow filling opening and can be used in sterile, antiseptic and sanitary environments without any operational or configuration difficulties.

The sensor preferably comprises a voltage generator producing a high-frequency alternating electrical field, two opposing, vertically arranged capacitor plates, which are given opposite, rapidly reversing charges by the voltage generator, and an ammeter. The high-frequency alternating electric current has a frequency in the range between approximately 500 kilohertz (kHz) and approximately 10 megahertz (MHz) and preferably a frequency of approximately 1 MHz.

The speed of the filling process is increased by the ability of the sensor to perform frequent measurements and at least 1,000 measurements per minute.

The sensor is able to determine the quantity of powdered substance within a time window of less than approximately 50 milliseconds (ms) and preferably less than approximately 10 milliseconds (ms), so that the reaction time is suitable even for very small quantities of powder or powdered substances and for processes which require high-speed filling.

In a preferred embodiment, the capacitor plates are separated from each other by a distance of approximately 5 millimeters (mm) to approximately 30 millimeters (mm) and this separation is preferably at least approximately 10% larger than the area covered by the powdered substance as it passes through the capacitor plates.

So that the filling process can be subjected to quality control, the control unit is able to convert the data acquired by the sensor into a control command for the vibrator within a period of approximately 10 ms.

In a preferred embodiment of the present invention, the filling process the supply vessel includes a capillary with the narrow exit opening located at one end. Such construction does not require a means for blocking the exit but instead provides that the cohesiveness of the powdered substance will prevent flow of the powdered substance under the effect of gravity. Accordingly, the powder stream can be controlled effectively by the action of the vibrator means. The device is thus suitable even for very small quantities of powder, powdered substances or other material and ensures an extremely accurate filling process. In addition, since a mechanical seal is not utilized, the device of this embodiment is particularly suitable for powders and powdered substances which are sensitive to abrasion.

The inventive method for the controlled filling of containers with a powdered substance comprises the steps of providing a supply vessel with a narrow exit opening for temporarily holding the powdered substance then generating vibrations to vibrate the supply vessel and thus to discharge a predetermined controlled quantity of the powdered substance into at least one container located below the supply vessel. The method also includes the steps of determining the quantity of powdered substance discharged from the supply vessel into the container; and controlling the vibration of the supply vessel on the basis of the result of the quantity determination step. The step of determining the quantity of powdered substance discharged includes the step of determining the quantity of powdered substance as it falls from the supply vessel into the container.

The step of determining the quantity of powdered substance discharged from the supply vessel into the container includes measuring the quantity of powder substance through the use of a capacitive sensor located between the supply vessel and the container. This measurement determines the quantity of powdered substance falling through the capacitive sensor during the filling process.

So that the containers can be filled reliably and accurately with the correct quantity of powdered substance, the quantity of powdered substance is determined within a time window of less than approximately 50 ms, and preferably a time window of less than approximately 10 ms. To provide the improved reliability and reaction time for vibrating the supply vessel, the data acquired by the sensor is converted into a control command for the vibrator means within a time period of approximately 10 ms.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional details, features, and advantages of the present invention can be derived from the following description and drawings in which:

FIG. 1 is a schematic view of an exemplary embodiment of the inventive device for the controlled filling of containers with powdered substances; and

FIG. 2 is a perspective schematic diagram of the sensor used in the present invention.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 is a schematic view of an exemplary embodiment of the inventive device for the controlled filling of containers with powdered substances. The device comprises a supply vessel 2, which is at least partially filled with a powdered substance 4. Supply vessel 2 is preferably clamped in a holder (not shown), which is mounted so that it is free to rotate. Supply vessel 2 is preferably made of high-grade steel, but many other materials such as glass, ceramic or other metals are which are also contemplated herein. In a preferred embodiment shown in FIG. 1, supply vessel 2 comprises at its lower end a capillary 5, which tapers to a point at the bottom, where a narrow exit opening 6 is located. The length and diameter of capillary 5 can be adapted to powdered substance 4 and to the geometry of the container 7 to be filled. Supply vessel 2 can also be of a two-part design in order to make it easier to replace capillary 5 with one of a different size, material, configuration or the like. Capillary 5 may enter the narrow openings of one or more containers, one of which is shown as container 7. Thus container 7 can be filled without contamination.

Other geometries are also conceivable, such as a small tube with a flat bottom and a narrow outlet bore as exit opening 6. Specifically, it is desired that no powdered substance 4 may flow out of exit opening 6 under the effect of gravity alone.

The flow of powdered substance 4 is generated by a vibrator means 8, which is connected to supply vessel 2. Vibrator means may include a variety of vibrating elements including piezoelectric elements, electromagnets or the like, or may be designed as a pneumatic vibrator, hi a preferred embodiment illustrated in FIG. 1, vibrator means includes a vibrator 8 which is shown as a piezoelectric vibrator and is preferably configured as the holder for supply vessel 2. Vibrator 8 can be actuated by way of a variable control current allowing supply vessel 2 to vibrate in a controlled and a variably controllable manner, preferably in a generally longitudinal direction consistent with the flow direction of powdered substance 4. Excitation in the direction transverse to flow of powdered substance 4 is also possible.

Sensor 12 is positioned below or underneath exit opening 6 of supply vessel 2. Sensor 12 is configured to determine the quantity of powdered substance 4 passing there through. Sensor 12 can be designed in a variety of configurations and may have various geometries. It will be appreciated that sensor 12 may be configured to form a plurality of parallel sensors (not shown) which can be set up in a very small working environment with very little space requirements.

Sensor 12 measures the quantity of powdered substance 4 falling through it and transmits measured data to a control unit 9, which converts the data acquired by sensor 12 into control commands to control vibrator 8. Thus the discharge of powdered substance 4 can be controlled directly as a reaction to the quantity of powdered substance 4 already present in container 7.

FIG. 2 illustrates a preferred embodiment of sensor 12. Sensor 12 is designed as a capacitive measuring sensor and comprises two vertically arranged capacitor plates 15, 16, which are positioned opposite each other. Powdered substance 4 falls between them. Capacitor plates 15, 16 are provided with opposite, rapidly reversing charges by a high-frequency AC voltage generator 13. The frequency of AC voltage generator 13 is between approximately 500 kHz and approximately 10 MHz, and preferably approximately 1 MHz. The charge states of capacitor plates 15, 16 upon application of opposite voltages are shown in the two parts of the figure. In the part on the left, capacitor plate 15 has a positive charge, and capacitor plate 16 has a negative charge, whereas, in the part on the right, capacitor plate 16 has a positive charge and capacitor plate 15 has a negative charge.

As a result of the reversing applied voltage U_(Generator)(t), very small changes in polarization are produced in powdered substance 4, which in itself represents an insulator, in the alternating electrical field. These very small polarization changes can be picked up by an ammeter 18. The measured current I_(M)(t) is proportional to the number of charged particles in powdered substance 4. Excellent results are obtained even during the time that the powder is falling and thus even during the extremely short time that powdered substance 4 is present in the area of sensor 12. Even a loose arrangement or a local splitting or expansion of the cluster of powder constituting the part of powdered substance 4 intended for container 7 does not have any negative effect on the measurement result. Sensor 12 is also insensitive to pressure variations and air currents, which offers considerable advantages in the area of aseptic or sterile production. In such environments, it is also advantageous that sensor 12 be easy to clean and to sterilize.

Sensor 12 is able to detect even very small quantities and also to integrate the values over time providing measurement of a loose powder stream of the type that may occur or be produced in this instance. This is especially advantageous, for example, in the case of powders for inhalation, because other metering systems can cause the powder to become compacted, which causes problems during the use of the product.

The details of the design of sensor 12 can vary widely, as long as the basic structure described herein in reference to FIG. 2 is preserved. In a preferred example, capacitor plates 15, 16 have a height of approximately 5- approximately 10 mm, preferably of approximately 6 mm, and the distance between them is in the range of approximately 5 to approximately 30 mm; preferably, however, it is at least approximately 10% wider than the area covered by the powdered substance as it passes through sensor 12.

In all cases, reference models or test samples corresponding to the type of powder must be recorded so that sensor 12 can be calibrated beforehand for the area of application in question. In this way it is possible to measure powdered substance 4 quantitatively and thus to control the discharge of the powdered substance accurately and reliably.

Container 7 may include a line of containers which may be transported to the filling station by a timed conveyor device. Through use of the device and method as described herein, with several sensors arranged next to each other and operating in parallel, it is possible to control the process of filling containers with powdered substance at a rate of more than 1,000 containers per minute. In this configuration, the data for powdered substance 4 is determined for a specific container and recorded by sensor 12 within a time window of less than approximately 50 ms, and preferably of less than approximately 10 ms. Because the data acquired by sensor 12 are converted by control unit 9 into a control command for vibrator means 8 within a time window of approximately 10 ms, the total reaction time of the system is preferably about approximately 20 ms.

Several inventive devices can be arranged and operated in a very small space. In many applications, a circular arrangement of the devices can be advantageous and is contemplated as one of many configuration alternatives of the present invention. The containers may be any shape, from extremely small blister pockets to large ampoules.

The term “powdered substance” as used herein, should be construed to include any powdered product, granular material or the like, and more specifically any powdered pharmaceutical product.

While the invention is shown in several forms, it is not limited to those embodiments illustrated, but is susceptible to various changes and modifications without departing from the spirit and scope of the invention. 

1. A device for the controlled filling of containers with powdered substance, comprising: a supply vessel with a narrow exit opening for temporarily holding the powdered substance and for discharging a predetermined quantity of the powdered substance into at least one container located below the supply vessel; vibrator means connected to the supply vessel for effecting the discharge of the powdered substance; a sensor for acquiring data and determining the quantity of powdered substance discharged from the supply vessel into the container; and a control unit, which is adapted to convert said data acquired by the sensor into control commands for the vibrator means, wherein the sensor is a capacitive sensor for the quantitative determination of the quantity of powdered substance falling through the sensor during the filling process and is located between the supply vessel and the container.
 2. The device according to claim 1, wherein the sensor comprises a voltage generator producing a high-frequency alternating electrical field: two opposing, vertically oriented capacitor plates, which are given opposite, rapidly reversing charges by the voltage generator; and an ammeter.
 3. The device according to claim 2, wherein the alternating electrical field has a frequency in the range from approximately 500 kHz to approximately 10 MHz.
 4. The device according to claim 1, wherein the sensor is adapted to perform a measurement.
 5. The device according to claim 4, wherein the sensor is adapted to perform at least approximately 1,000 measurements per minute.
 6. The device according to claim 1, wherein the sensor is adapted to determine the quantity of powdered substance within a time window of less than approximately 50 ms.
 7. The device according to claim 2, wherein the distance between the capacitor plates is in the range of approximately 5 mm to approximately 30 mm.
 8. The device according to claim 1, wherein the control unit is adapted to convert the data acquired by the sensor into a control command for the vibrator means within a time period of approximately 10 ms.
 9. The device according to claim 1, wherein the supply vessel comprises a capillary, at the end of which the narrow exit opening is located.
 10. A method for the controlled filling of containers with powdered substance comprising the steps of: providing a supply vessel having a narrow exit opening for temporarily holding the powdered substance; generating vibrations to vibrate the supply vessel and thus to discharge a predetermined quantity of the powdered substance into at least one container located below the supply vessel; determining the quantity of powdered substance discharged from the supply vessel into the container; and controlling the vibration of the supply vessel based on the result of the step of determining the quantity of powdered substance discharged, wherein the step of determining the quantity of powder substance discharged comprises the step of determining the quantity of powdered substance as it falls from the supply vessel into the container.
 11. The method according to claim 10, wherein the step of determining the quantity of powdered substance discharged from the supply vessel into the container includes measuring the quantity of powder substance through the use of a capacitive sensor located between the supply vessel and the container.
 12. The method according to claim 10, wherein the quantity of powdered substance is determined within a time window of less than approximately 50 ms.
 13. The method according to claim 10, wherein the data acquired by the sensor are converted within a time period of approximately 10 ms into a control command for a vibrator means responsible for vibrating the supply vessel. 